From: David Woodhouse Drivers registering IRQ handlers with SA_SHIRQ really ought to be able to handle an interrupt happening before request_irq() returns. They also ought to be able to handle an interrupt happening during the start of their call to free_irq(). Let's test that hypothesis.... Signed-off-by: David Woodhouse Cc: Arjan van de Ven Signed-off-by: Andrew Morton --- kernel/irq/manage.c | 26 ++++++++++++++++++++++++++ lib/Kconfig.debug | 9 +++++++++ 2 files changed, 35 insertions(+) diff -puN kernel/irq/manage.c~debug-shared-irqs kernel/irq/manage.c --- devel/kernel/irq/manage.c~debug-shared-irqs 2006-01-08 22:21:42.000000000 -0800 +++ devel-akpm/kernel/irq/manage.c 2006-01-08 22:21:42.000000000 -0800 @@ -238,6 +238,10 @@ int setup_irq(unsigned int irq, struct i return 0; } +#ifdef CONFIG_DEBUG_SHIRQ +static struct pt_regs shirq_fakeregs; +#endif + /** * free_irq - free an interrupt * @irq: Interrupt line to free @@ -257,6 +261,7 @@ void free_irq(unsigned int irq, void *de struct irq_desc *desc; struct irqaction **p; unsigned long flags; + irqreturn_t (*handler)(int, void *, struct pt_regs *) = NULL; if (irq >= NR_IRQS) return; @@ -295,6 +300,8 @@ void free_irq(unsigned int irq, void *de /* Make sure it's not being used on another CPU */ synchronize_irq(irq); + if (action->flags & SA_SHIRQ) + handler = action->handler; kfree(action); return; } @@ -302,6 +309,15 @@ void free_irq(unsigned int irq, void *de spin_unlock_irqrestore(&desc->lock,flags); return; } +#ifdef CONFIG_DEBUG_SHIRQ + if (handler) { + /* It's a shared IRQ -- the driver ought to be prepared for it to happen + even now it's being freed, so let's make sure.... + We do this after actually deregistering it, to make sure that a 'real' + IRQ doesn't run in parallel with our fake. */ + handler(irq, dev_id, &shirq_fakeregs); + } +#endif } EXPORT_SYMBOL(free_irq); @@ -368,6 +384,16 @@ int request_irq(unsigned int irq, select_smp_affinity(irq); +#ifdef CONFIG_DEBUG_SHIRQ + if (irqflags & SA_SHIRQ) { + /* It's a shared IRQ -- the driver ought to be prepared for it to happen + immediately, so let's make sure.... + We do this before actually registering it, to make sure that a 'real' + IRQ doesn't run in parallel with our fake. */ + handler(irq, dev_id, &shirq_fakeregs); + } +#endif + retval = setup_irq(irq, action); if (retval) kfree(action); diff -puN lib/Kconfig.debug~debug-shared-irqs lib/Kconfig.debug --- devel/lib/Kconfig.debug~debug-shared-irqs 2006-01-08 22:21:42.000000000 -0800 +++ devel-akpm/lib/Kconfig.debug 2006-01-08 22:21:42.000000000 -0800 @@ -195,6 +195,15 @@ config DEBUG_VM If unsure, say N. +config DEBUG_SHIRQ + bool "Debug shared IRQ handlers" + depends on GENERIC_HARDIRQS + help + Enable this to generate a spurious interrupt as soon as a shared interrupt + handler is registered, and just before one is deregistered. Drivers ought + to be able to handle interrupts coming in at those some; some don't and + need to be caught. + config FRAME_POINTER bool "Compile the kernel with frame pointers" depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML) _